Electrode systems are known from various publications, such as US 2002/0188338 A1, US 2002/0188340 A1, or US 2002/0193860 A1.
These known devices have an oblong, hose-like electrode body, on whose distal end a helical screw-in electrode is displaceable between a retracted passive position inside the electrode body and an extended active fixing position. The purpose of this screw-in electrode seated on the tip of the electrode device is its stable and permanent anchoring in cardiological tissue suitable for the particular diagnosis and treatment. In order to ensure this, the helical screw-in electrode is screwed into the tissue like a corkscrew, which is implemented through a rotational movement of the electrode supply line powering the screw-in electrode during extension of the screw-in electrode from the retracted passive position into the extended fixing position.
The conversion of the rotational movement of the electrode supply line into an additional translational movement of the screw-in electrode for extension into the fixing position is caused with the aid of a spindle-type cam controller. In the electrode devices according to the above-mentioned publications, a cam projection situated on the electrode body engages directly in the coil of the screw-in electrode for this purpose. Because of the positioning of the cam, the electrode body on the distal end of the electrode device on which it is mounted must be designed as relatively rigid and stable. This prevents a more flexible design of the distal end, which is viewed as advantageous in modern implantable electrode devices in regard to an implantation procedure with as little irritation as possible.
In this context, a certain spatial separation between the cam controller for the translational movement of the screw-in electrode and the electrode itself is known from US 2003/0144722 A1. The screw-in electrode is situated having its proximal end on a bearing body therein, which is guided displaceably like a spindle using an external thread in a corresponding internal thread in the electrode body. However, a separate stylet must be inserted through the electrode body and coupled rotatably to the bearing body for the rotational drive of the bearing body.